Answer:
To find the sum of two numbers add them together C:
Step-by-step explanation:
example: the sum of 3 and 4 is 7
the sum means its addition
Answer:

Step-by-step explanation:
Elimination method:


Add these equations to eliminate x:

Then solve
for y:



Write down an original equation:

Substitute 4 for y in
:




{
and
} ⇒ 
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<em>hope this helps...</em>
Answer:
Equation: 6+d-18
d = difference of a number and eighteen
Idk if it helps. :|
108 miles 3 hours = 36 mph upstream
108 miles 2 hours = 54 mph downstream
bv = boat velocity in still water
cv = current velocity
bv -cv = 36
bv +cv = 54 Adding both equations
2*bv = 90
boat velocity in still water = 45 mph
since bv + cv = 54
then we know the current velocity = 9 mph
Hi.
An example of a fraction equivalence chain is this:

You can keep multiplying

by 2 to get a fraction chain.
Hope this helps!